Single-turn conductor pattern for microminiature core assemblies in a multitransducer head

ABSTRACT

One-turn conductor patterns for a multi-core head assembly are designed to provide for a minimum of cable connections and to maximize track width. The specific configuration of conductor patterns exhibiting these advantages may vary, except for a common criterion. The terminal pads of the conductor patterns to which electronic read/write circuit cables are connected are minimized to the greatest extent possible by a conductor pattern layout that results in one terminal pad being common to as many one for each core, single-turn conductors, as possible.

United States Patent Billawala June 10, 1975 [75] Inventor: Shahbuddin A. Billawala, Thousand Oaks, Calif.

[73] Assignee: Burroughs Corporation, Detroit,

Mich.

[22] Filed: Oct. 9, 1973 [21] Appl. No.: 404,804

[52] US. Cl. 360/123 [51] Int. Cl. ..G1lb 5/20 [58] Field of Search 179/100.2 C, 100.2 CH; 340/1741 F; 346/74 MC; 29/603; 360/121, 123, 125, 127

[56] References Cited UNITED STATES PATENTS 2,647,167 7/1953 Rettinger 179/1002 C 3,114,009 12/1963 Camras et a1. 179/1002 CH 3,715,522 2/1973 Tsukagoshi 340/1741 F 3,781,476 12/1973 Hanazono et a1 360/125 OTHER PUBLICATIONS Batch Fabricated Tunnel Erase Head, 1.B.M. Tech. Disc. Bul1., Davy, Vol. 15, No. 6, Nov. 1972, pg. 2036.

Primary ExaminerBernard Konick Assistant ExaminerR. S. Tupper Attorney, Agent, or FirmAlbin H. Gess; Nathan Cass; K. R. Peterson [57] ABSTRACT One-turn conductor patterns for a multi-core head assembly are designed to provide for a minimum of cable connections and to maximize track width. The specific configuration of conductor patterns exhibiting these advantages may vary, except for a common criterion. The terminal pads of the conductor patterns to which electronic read/write circuit cables are connected are minimized to the greatest extent possible by a conductor pattern layout that results in one terminal pad being common to as many one for each core, single-turn conductors, as possible.

4 Claims, 5 Drawing Figures SHEET PATENTEDJUH 10 I975 t 1 SINGLE-TURN CONDUCTOR PATTERN FOR MICROMINIATURE CORE ASSEMBLIES IN A MULTITRANSDUCER HEAD BACKGROUND OF THE INVENTION The present invention relates generally to improve ments in electromagnetic transducers and more particularly pertains to new and improved multitransducer head assemblies wherein the plurality of microminiature core assemblies and conductors for the multitransducer head assembly are simultaneously manufactured by deposited film techniques.

In the field of deposited film transducers, the trend of development has been towards miniaturization of the core assemblies and conductors making up the transducers so that more transducers can be placed within a certain size head housing. This trend manifested itself because of the desire to increase track density on the magnetic recording medium that cooperates with the multitransducer head, and the desire to reduce manufacturing costs. Prior art deposited film transducers generally utilized multiple-turn conductor patterns. An example of a patent directed to such a transducer is U.S. Pat. No. 3,344,237. The manufacturing process for a multiple-turn conductor pattern transducing head. however, can be expensive, and does not lend itself to microminiaturization of the head assembly.

With an intent to reduce manufacturing cost, the prior art, an example of which can be found in U.S. Pat. No. 3,157,748. attempted the use of a single-turn conductor pattern for the core assemblies in a multitransducer head. The use of single-turn conductor patterns, while reducing manufacturing cost, introduced a whole new set of problems that made it undesirable to manufacture a multi-transducer head with only a single-turn conductor per core. For example, the use of the singleturn conductor for each core assembly in the transducer head has the disadvantage of a low signal amplitude during a readback operation. To overcome this problem, more complex and expensive electronic read circuitry had to be utilized. Thus, while reducing the fabrication cost of the multitransducer head, the fabrication cost of the electronic circuitry was increased. Also, when the prior art attempted microminiaturization of such a multitransducer head, the cabling connections between the head and the read/write electronics became extremely critical because of the many individual conductors, two for each single turn conductor, per core, that needed to be connected to the conductor pattern. The cabling problem was highlighted by such negative factors as an undesirably high conductor resistance in the cable; an insufficiently flexible cable assembly, because of the multiplicity of individual conductors needed in the cable; high manufacturing cost of the cable assembly, because of the many individual conductors; and high connection cost because of the many individual conductor ends that have to be con nected to the conductor pattern.

SUMMARY OF THE INVENTION It is an object of this invention to significantly reduce the number of conductor cable connections to the conductor pattern in a multitransducer head assembly.

It is another object of this invention to increase the track width of a multitransducer head assembly.

These and other objects that will become self-evident are attained by utilizing a one-turn conductor pattern for a multi-core head assembly that provides terminal conductor connection pads that service a plurality of single-turn conductors, one for each core in the head. A variety of conductor patterns, all having this common criteria, and advantages result, are possible.

BRIEF DESCRIPTION OF THE DRAWINGSj Other objects and many of the attendant advantages of this invention will be readily understood by reference to the following detailed description in which like reference numerals designate like parts throughout the figures thereof and wherein:

FIG. 1 is an exploded view of a broken away section of the basic elements of a film deposited multitransducer head assembly.

FIG. 2 is a top view of a conductor pattern, according to the present invention, that could be used in the film deposited transducer of FIG. 1.

FIG. 3 is a top view of a conductor pattern, according to the present invention, that could be used in the transducer head assembly of FIG. 1.

FIG. 4 is a top view ofa conductor pattern, according to the present invention, that could be used in the multitransducer head assembly of FIG. 1.

FIG. 5 is a top view of a conductor pattern, according to the present invention, that could be used in the multitransducer head assembly of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, the conductor pattern 15 forms one layer of a multi-layered laminate of various materials that constitute the multitransducer head assembly. A substrate 11 of insulating material such as Cornings glass ceramic or any other suitable ceramic material or, sapphire or any other suitable monocrystalline material, supports subsequent layers of materials that make up the core assemblies and conductors of the transducers in the head. A layer of paramagnetic material 13 is deposited by well-known vacuum deposition techniques or photofabrication techniques on the substrate material 11. This paramagnetic material may be iron or permalloy or any other such suitable material. This strip of paramagnetic material may be divided into individual segments, as shown, by etching channels 14 into it. If this paramagnetic layer is divided into segments in this way, there would be one segment for each defined transducer. In some cases it may be more desirable to not divide this layer into segments. In such an instance, a strip of insulating material (not shown) is deposited on the permalloy layer 13. This insulating material may be aluminum oxide, magnesium flouride, or any other such suitable material.

A conductor pattern 15 having a single-turn conductor 16 and an opening or window 18 for each defined transducer is made up of material that is conducive to electron flow, such as copper, iridium, or other similar material. This conductor pattern is deposited directly on the permalloy layer 13 if it is segmented. The conductor pattern is deposited by the use of well known vacuum deposition techniques or photofabrication techniques. If the permalloy layer 13 is not segmented, another layer of insulation (not shown) is deposited on the conductor pattern 15. A second layer 17 of paramagnetic material is deposited on the conductor pattern 15. This second layer 17 of paramagnetic material will be insulated from the conductor pattern only if it is not segmented. as shown, by etched channels 20. The segmented paramagnetic material layers 13 and 17 have pairs of segments, one from layer 13 and one from layer 17,that make contact with each other in the windows 18 of the conductor pattern 15, thereby forming a multiplicity of individual core assemblies, each core having a single winding 16 and a U-shaped paramagnetic element formed by a particular segment pair from the paramagnetic layers 13 and 17. If the paramagnetic material layers 13 and 17 are not segmented, the layers 13 and 17 making contact in the window 18 of the conductor pattern would form a multiplicity of connected core assemblies. Use of insulation between the conductor pattern and the paramagnetic layers in this case prevents cross-talk between the plurality of resulting transducers.

The thickness of the conductor pattern layer 15, as illustrated in FIG. 1, will determine the magnetic core gap, that is, the separation of the two paramagnetic layers 13 and 17. However, it is contemplated that if a different size core gap than the thickness of the conductor pattern 15 will provide. is desired, an additional layer of conductive or non-conductive material may be interposed between the two paramagnetic material layers 13 and 17.

Referring now to FIG. 2, an illustration of a partial conductor pattern according to this invention, is shown. The pattern shown defines four transducers in a multitransducer head assembled in the manner illustrated in FIG. 1. Four single-turn conductors 19, 21, 23, and are disposed along a single straight line. Each conductor is separated from the other by insulating gaps 27, 29, 31. A common terminal or cable con nection pad 41 is connected to either a second or first end of each single-turn conductor. For example, the terminal pad 41 is connected to the second end of conductor 19, the first end of conductor 21, the second end of conductor 23, and the first end of conductor 25. The other ends of the single-turn conductors 19, 21, 23, and 25 are connected to their respective terminal or connection pads 33, 35, 37, and 39. Thus, terminal connection pad 33 is connected to the first end of conductor l9. Terminal connection pad 35 is connected to the second end of conductor 21. Terminal connection pad 37 is connected to the first end of conductor 23. Terminal connection pad 39 is connected to the second end of conductor 25. It should be understood that this particular pattern may continue for N conductors, only four conductors being shown for the purpose of simplifying the disclosure.

Referring now to FIG. 3, which shows an alternate conductor pattern according to this invention, the plurality of single-turn conductors 43, 45, 47, and 49 are again laid out in a single straight line. Each of the terminal or connector pads in the conductor pattern is common to two adjacent single-turn conductors. Thus, for example, conductor pad 51 is connected to the second end of single-turn conductor 43 and the first end of single-turn conductor 45. Conductor pad 57 is connected to the second end of single-turn conductor 45 and the first end of single-turn conductor 47. Conductor pad 53 is connected to the second end of single-turn conductor 47 and the first end of single-turn conductor 49. As can be seen from this figure, this conductor pattern does not utilize insulating gaps between the conductor lengths 43, 45, 47, and 49 that was evident in the conductor pattern of FIG. 2. By not using these insulating gaps between the. individual single-turn conductors, the length of the single-turn conductors may be increased, thereby increasing the track width of the individual transducers in the head which causes an increase in the read signal amplitude. However, this advantage carries with it the disadvantage that removing the insulating gaps between the individual single-turn conductors increases interference between the transducers known as cross-talk.

Referring now to FIG. 4, which illustrates another conductor pattern according to this invention, a common terminal connector pad 77 is connected to one end of each of the individual single-turn conductors 61, 63, '65, 67. Thus, terminal pad 77 is connected to the first end of conductor 61, the first end of conductor 63, the first end of conductor 65, and the first end of conductor 67. The other terminals pads are connected to the other ends of, or in this case, the second end of their respective single-turn conductor. Thus, pad 69 is connected to the second end of conductor 61. Pad 71 is connected to the second end of conductor 63. Pad 73 is connected to the second end of conductor 65. Pad 75 is connected to the second end of conductor 67. As can be seen from the figure, this particular pattern utilizes an insulating gap between each of the transducers.

Referring now to FIG. 5, which illustrates another conductor pattern according to this invention, four single-turn conductors 79, 81, 83, and are laid along a common straight line. Each of these individual conductors are separated by insulating gaps 87, 89, and 91. As can be seen from the figure, insulating gap 89 completely separates the conductors and the pad connections between adjacent pairs of conductor patterns. This particular conductor pattern requires three terminal or connecting pads for every two single-turn conductors. Thus, for example, terminal 93 is connected to the second end of conductor 79, and the first end of conductor 81. Pad 97 is connected to the first end of conductor 79. Pad 99 is connected to the second end of conductor 81. Pad is connected to the second end of conductor 83, and the first end of conductor 85. Pad 101 is connected to the first end of conductor 83. Pad 103 is connected to the second end of conductor 85.

From the foregoing discussion, it is clear that an improved conductor pattern for a microminiature core multitransducer head assembly has been disclosed. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced'otherwise than as specifically described.

What is claimed is:

1. In a multitransducer head assembly having a laminate structure of a substrate supporting a first layer of paramagnetic material, a layer of conducting material insulated from said first layer of paramagnetic material by a first layer of insulating material between said first layer of paramagnetic material and said layer of conducting material, a second layer of paramagnetic material insulated from said layer of conducting material by a second layer of insulating material between said layer of conducting material and said second layer of paramagnetic material, said second layer of paramagnetic material contacting said first layer of paramagnetic material at spaced locations thereof so as to form a plurality of individual magnetic cores in a straight line, said layer of conducting material formed to provide an improved single-turn conductor pattern for a plurality of individual transducers in said head. said conductor pattern comprising:

a plurality of single-turn electron paths disposed in a straight line. in the same plane, each said path defining a transducing gap and having a first and a second end;

one terminal pad connected to the first end of each of said plurality of electron paths; and

a plurality of terminal pads, equal in number to said plurality of single-turn electron paths. one terminal pad connected to the second end of each one of said plurality of single-turn electron paths.

2. The conductor patterns of claim 1 wherein:

said plurality of terminal pads and said one terminal pad are connected to the first and second ends of said electron paths by conductive paths providing non-conductive gaps between the ends of one electron path and the ends of a subsequent or preceding electron path,

3. In a multitransducer head assembly having a laminate structure of a substrate supporting a first layer of paramagnetic material, said first layer of paramagnetic material divided into individual segments, a layer of conducting material, and a second layer of paramagnetic material. said second layer of paramagnetic material divided into individual segments paired with and contacting the segments of said first layer of paramagnetic material to define individual cores, said layer of conducting material forming an improved single-turn conductor pattern for a plurality of individual transducers in said head, said conductor pattern comprising:

a plurality of single-turn electron paths disposed in a straight line, in the same plane, each said path defining a transducing gap and having identical first and a second ends;

one terminal pad connected to every second end of one electron path and every first end of an adjacent electron path for each pair of electron paths in said plurality of electron paths; and g a plurality of terminal pads. equal in number to said plurality of electron paths, one terminal pad connected to the end of each said plurality of electron paths not having said one terminal pad connected to it.

4. The conductor pattern of claim 3 wherein said plu rality of terminal pads and said one terminal pad are connected to the first and second ends of said electron paths by conductive paths providing nonconductive gaps between the ends of one electron path and the ends of a subsequent or preceding electron path. 

1. In a multitransducer head assembly having a laminate structure of a substrate supporting a first layer of paramagnetic material, a layer of conducting material insulated from said first layer of paramagnetic material by a first layer of insulating material between said first layer of paramagnetic material and said layer of conducting material, a second layer of paramagnetic material insulated from said layer of conducting material by a second layer of insulating material between said layer of conducting material and said second layer of paramagnetic material, said second layer of paramagnetic material contacting said first layer of paramagnetic material at spaced locations thereof so as to form a plurality of individual magnetic cores in a straight line, said layer of conducting material formed to provide an improved single-turn conductor pattern for a plurality of individual transducers in said head, said conductor pattern comprising: a plurality of single-turn electron paths disposed in a straight line, in the same plane, each said path defining a transducing gap and having a first and a second end; one terminal pad connected to the first end of each of said plurality of electron paths; and a plurality of terminal pads, equal in number to said plurality of single-turn electron paths, one terminal pad connected to the second end of each one of said plurality of single-turn electron paths.
 2. The conductor patterns of claim 1 wherein: said plurality of terminal pads and said one terminal pad are connected to the first and second ends of said electron paths by conductive paths providing non-conductive gaps between the ends of one electron path and the ends of a subsequent or preceding electron path.
 3. In a multitransducer head assembly having a Laminate structure of a substrate supporting a first layer of paramagnetic material, said first layer of paramagnetic material divided into individual segments, a layer of conducting material, and a second layer of paramagnetic material, said second layer of paramagnetic material divided into individual segments paired with and contacting the segments of said first layer of paramagnetic material to define individual cores, said layer of conducting material forming an improved single-turn conductor pattern for a plurality of individual transducers in said head, said conductor pattern comprising: a plurality of single-turn electron paths disposed in a straight line, in the same plane, each said path defining a transducing gap and having identical first and a second ends; one terminal pad connected to every second end of one electron path and every first end of an adjacent electron path for each pair of electron paths in said plurality of electron paths; and a plurality of terminal pads, equal in number to said plurality of electron paths, one terminal pad connected to the end of each said plurality of electron paths not having said one terminal pad connected to it.
 4. The conductor pattern of claim 3 wherein said plurality of terminal pads and said one terminal pad are connected to the first and second ends of said electron paths by conductive paths providing non-conductive gaps between the ends of one electron path and the ends of a subsequent or preceding electron path. 